Once there, according to the Oxford Dictionary of National Biography, "He formed part of a new élite of ‘competition-wallahs’ which intellectually outshone the earlier generation of Punjabi military political officials and well-connected alumni of Haileybury College.

The censuses of India carried out in 1865, 1872 and 1881 had attempted to classify people according to the Brahmanic ritual ranking system of varna but this proved not to reflect the realities of social relationships, however much it might have met with approval from scholars of Sanskrit and ancient texts.

[10] Together with John Collinson Nesfield's Brief view of the caste system of the North-Western Provinces and Oudh, published in 1885, Ibbetson's 1883 Report was influential in bringing about a change in categorisation method throughout the country.

He argued that the conventional belief in caste as a purely Hindu construct was erroneous, that people who had converted from Hinduism to Islam remained affected by the system, and that therefore it should be viewed more as a social than a religious mechanism.

He pointed out that there were Brahmins who were viewed as being outcastes even by the lowest ritual rank, the Shudra, and that the latter term was primarily used as a form of abuse rather than in any categorical sense.

Despite their influence on the processes adopted for the 1891 census, the ideas of Ibbetson and Nesfield subsequently lost favour in the administration of the British Raj.

[10]The anecdotal evidence of a racial basis for caste, which could be traced back to the late-18th century speculations of William Jones,[11] was being buttressed by the relatively new field of study known as anthropometry and this gave rise to a form of scientific racism epitomised by the work of people such as Herbert Hope Risley, who became Census Commissioner for India in 1901.

[10] Bates remarks that Ibbetson's "classification of castes, however logical and useful it might have proven, lacked a 'scientific' basis, as well as completely neglecting the problem of status."

In the longer term, however, Ibbetson's theories have attracted support from John Henry Hutton and Edmund Leach and have been "cherished by successive generations of non-Marxist, non-Dumontian historians and anthropologists working in the classical British tradition of structural-functionalism, first established by Radcliffe Brown.